Ni₅P₄-NiP₂-Ni₂P Nanocomposites Tangled with N-Doped Carbon for Enhanced Electrochemical Hydrogen Evolution in Acidic and Alkaline Solutions

Heterostructured non-precious metal phosphides have attracted increasing attention in the development of high-performance catalysts for hydrogen evolution reaction (HER), particularly in acidic media. Herein, a catalyst composed of ternary Ni₅P₄-NiP₂-Ni₂P nanocomposites and N-doped carbon nanotubes/carbon particulates (Ni₅P₄-NiP₂-Ni₂P/NC) was prepared from a Ni-containing hybrid precursor through approaches of a successive carbonization and phosphating reaction. Benefiting from the synergistic effect from three-component nickel phosphides and the support role of porous carbon network, the Ni₅P₄-NiP₂-Ni₂P/N-doped carbon catalyst presents the promising HER performance with overpotentials of 168 and 202 mV at the current density of 10 mA cm⁻² and Tafel slopes of 69.0 and 74 mV dec⁻¹ in both acidic and alkaline solutions, respectively, which surpasses the Ni₂P/N-doped carbon counterpart. This work provides an effective strategy for the preparation and development of highly efficient HER non-precious metal electrocatalysts by creating heterostructure in acidic and alkaline media.